26 research outputs found
Nitrogen Tetroxide to Mixed Oxides of Nitrogen: History, Usage, Synthesis, and Composition Determination
No full textSince as early as the 1920s, dinitrogen tetroxide (N2O4) has been regarded as a promising oxidizer in rocket propulsion systems. In more recent times, its predecessor, mixed oxides of nitrogen (MON), remains a top contender among oxidizers, due to its unique characteristics such as low freezing temperature and compatibility with common spacecraft materials. Today, these N2O4- based oxidizers are the preferred choice in many upper stages, launch escape systems, reaction control systems, liquid apogee engines, and in-space primary propulsion systems. N2O4-based oxidizers are a key factor in rocket propulsion, and thoroughly understanding their history, development, characteristics, synthesis, and composition analysis are crucial for space exploration today and into the future.To fully understand and predict the physical properties of a MON sample, it is important to measure and quantify its chemical composition. The recommended method for MON composition analysis, as prescribed by the Department of Defense’s Defense Specification (MIL-SPEC) document on N2O4, involves the oxidation of NO and dinitrogen trioxide (N2O3) in the MON sample to determine their amounts. An equation unofficially called the “MIL-SPEC equation” is then used to determine the amount of NO needed to mix with N2O4to synthesize that particular MON sample. However, no explanation is given as to how the equation was derived, or its significance.This thesis aims to collect and organize key information on the synthesis, handling, and composition analysis of MON propellant. First, the history of development of N2O4-based oxidizers was researched, and current and future uses of N2O4and MON propellants were identified. Then a method for synthesis and composition analysis was devised and tested. Water contamination was expected of skewing the results, so the process of water contamination was examined analytically. Then a detailed derivation of the MIL-SPEC equation was conducted, to fully understand its mechanics. An attempt was then made to reverse-engineer an unexplained numerical value in the equation, labeled by the author as the “solubility factor”. Several derivations were provided with varying degrees of complexity, producing alternative solubility factors of varying accuracies. Finally, experimental data was applied to these derived, hypothetical solubility factors and the MIL-SPEC solubility factor, with the intent of determining whether improvements could be made to the MON composition determination process.The results suggest that the MIL-SPEC equation is sufficient for providing a relatively accurate measurement of the composition of a MON sample, while also being easy to implement, both in taking the necessary measurements and in conducting the numerical calculation. However, some minor adjustments to the equation could produce consistently more accurate composition measurements without adding any more difficulty or complication
John of Damascus and heresy : a basis for understanding modern heresy
No full textThis study investigates the understanding of heresy and the heretic according to Saint John of Damascus. For him, a heretic was any Christian who, by wilful choice, departs from the one orthodox tradition by adopting a personal opinion on the common faith which he intends to institute as sole truth. Our research is divided into two parts and aims to apply John of Damascus’ understanding of the recurring identity of the Christian heretic and his behaviour.
By using historical-theological, interdisciplinary and diachronical approaches, the author demonstrates through two case studies, namely, the Dutch Reformed Churches and Apartheid, and Kimbanguism, that this Church Father, who is the ‘seal of the patristic era,’ remains a relevant authority for our comprehension of heresy and the heretic
Abstract simplicity of locally compact Kac-Moody groups
No full textIn this paper, we establish that complete Kac-Moody groups over finite fields are abstractly simple. The proof makes essential use of Mathieu and Rousseau's construction of complete Kac-Moody groups over fields. This construction has the advantage that both real and imaginary root spaces of the Lie algebra lift to root subgroups over arbitrary fields. A key point in our proof is the fact, of independent interest, that both real and imaginary root subgroups are contracted by conjugation of positive powers of suitable Weyl group elements. © The Author 2014
A partnership for prosperity agency : a case study of InnerCHANGE South Africa
No full textPractical ways to serve African communities of poverty motivated this case study. It explores
how the church could be missional as an agent of prosperity in communities of poverty.
It reflects on partnership between a missional team, InnerCHANGE, with businesses in order
to provide jobs for ordinary people, especially the youth who are a marginalised section of our
society in terms of employment. This article uses a biblical interpretive framework from
Jeremiah 29:7 to reflect on the role of the church in society. The author interviewed
15 employment beneficiaries and 18 parents or guardians in order to learn how employment
has improved the quality of life of individuals, households and their community of residence.
The findings led to a reflection which captures successes as well as growth areas to be
considered by InnerCHANGE in its efforts to become an example of the church as a prosperity
agent in society.https://theologiaviatorum.org/am2021Science of Religion and Missiolog
Índice analítico de la revista Arte y Medicina (1952-1959)
No full textSome biographic data of Dr. Jean Francois Timothee Tuzet y Cerdiat are given. Jean Francois was a French man who settled down in Cuba, where he founded a journal aimed at facilitating the access of the Cuban doctors to universal culture. As a result of the revision of all the collection, entitled "Arte y Medicina", and in order to know everything that happened on its pages since May 1952, when it started to circulate, until it disappeared in March 1959, its most important formal and content aspects are reviewed and the papers published in each of its issues are described. This description presented as a bibliographic index is complemented with other iconographic, author and subject indexes
Christian leadership in a South African township community : a reflection on nepotism and its impact on society
No full textThe author reflects on the reality of nepotism in Christian leadership as he has observed in the
township of Soshanguve and many other African poverty-stricken communities he has lived
in. The leadership of churches in those areas seems to run in the family. This model tends to
have a disempowering effect on the other church members in terms of taking responsibility or
initiating projects that could expand the impact of the church beyond the borders of its walls.
This article recognises the positive impact of nepotism, but it mostly stresses on the negative
impact of nepotism on the democratisation of power in the church and society. It uses music,
a critical vehicle of knowledge acquisition in Africa, to stress upon the fact that Christian
leaders should be equipped to participate in the common good, help in the empowerment of
ordinary people around them, starting with their members and be altruistic, like Jesus, and
work beyond the boundaries of their families.http://www.hts.org.zaam2020Science of Religion and Missiolog
Migration to South Africa : a missional reflection of a refugee using Jeremiah 29:4–12 as an interpretive framework
No full textThis article is an auto-ethnographic reflection on the phenomenon of migration. The latter is
on the increase throughout the world. This article focusses on the context of South Africa
where there seems to be a negative perception of refugees in communities of poverty. It uses
Jeremiah 29:4–12 as an interpretative framework to, on the one hand, analyse the negative
perceptions of refugees and, on the other hand, propose ways refugees could be assets to their
host communities. The author is part of a missional team that serves in some South African
communities of poverty where refugees have experienced a great deal of discrimination. He
reflects on his status as a refugee and a mission worker to point out a constructive role a
refugee could play in society as a Christian. He refers to this role as good news agency. The
article alludes to practical examples where a constructive role in a community has led refugees
to be seen as assets to their communities. It concludes by stressing that the negative perception
of refugees in South African communities of poverty may be an implicit collective longing
local residents have for good news agents around them regardless of their countries of origin.https://theologiaviatorum.orgam2021Science of Religion and Missiolog
Nurturing agency in emerging adults of local churches : a case study from Soshanguve
No full textDATA AVILABILITY STATEMENT: Data sharing is not applicable to this article. The data collected through interviews are confidential information available to the author alone.Emerging adults (age 35 and below) are the majority of the African population. In South Africa, for example, emerging adults make 63.9% of its population. This age group seems to be marginalised in Christian congregations of the township of Soshanguve where this research was conducted. This research is a case study that interviewed 30 de-churched emerging adults from different denominations to make its conclusions. It is stressing how the church could see the emerging adults’ empowerment as its contribution to building an inclusive society. It was found out that many people under the age of 35 years are leaving their local churches because they feel that their voices are undervalued, and they do not have fulfilling roles to play. It was concluded that some de-churched emerging adults are eager to exercise their agency in making their voices heard and playing fulfilling roles in a missional community structure outside their previous congregations. Many others just complained about the marginalisation they experienced in their previous congregations, but they did not exercise their agency to help build a church they would love to be part of. Marginalisation could, therefore, be an
opportunity to create an inclusive community. It could also remain an eternal wound for other people who may just be finger-pointing perpetrators of marginalisation without demonstrating a different praxis.http://www.hts.org.zaScience of Religion and Missiolog
Successful closure of a rectovesical fistula after radical prostatectomy using endoscopic submucosal dissection combined with an over-the-scope clip
No full textInternational audienc
Connecting people and ideas from around the world: global innovation platforms for next-generation ecology and beyond
No full textabstract: We present a case for using Global Community Innovation Platforms (GCIPs), an approach to improve innovation and knowledge exchange in international scientific communities through a common and open online infrastructure. We highlight the value of GCIPs by focusing on recent efforts targeting the ecological sciences, where GCIPs are of high relevance given the urgent need for interdisciplinary, geographical, and cross-sector collaboration to cope with growing challenges to the environment as well as the scientific community itself. Amidst the emergence of new international institutions, organizations, and meetings, GCIPs provide a stable international infrastructure for rapid and long-term coordination that can be accessed by any individual. This accessibility can be especially important for researchers early in their careers. Recent examples of early-career GCIPs complement an array of existing options for early-career scientists to improve skill sets, increase academic and social impact, and broaden career opportunities. We provide a number of examples of existing early-career initiatives that incorporate elements from the GCIPs approach, and highlight an in-depth case study from the ecological sciences: the International Network of Next-Generation Ecologists (INNGE), initiated in 2010 with support from the International Association for Ecology and 20 member institutions from six continents
